I&#39;ve sailed both boards extensively in the last year. Even though the 115 doesn&#39;t have much more volume it will carry a bigger sail better. The 104 at my weight, 84 kg, starts to bog down with sails much bigger than 6.6 while the 115 carries an extra 0.5 meter quite well. At your lighter weight you can make somewhat bigger sails work, but the 8.2 will be big even on the 115. Regarding control in 12-20 the 115 won&#39;t be too big. Considering what sails you want to use, I&#39;m inclined to recommend the 126. One of my sailing partners who is close to your weight and height has one that he routinely uses with a 6.6 and 7.6 Neutron and he doesn&#39;t find it hard to control on very choppy water in the wind ranges you mentioned.

I am 71 kg, 180cm and I have sailed both boards. I have sailed the 104 with a Nitro4 race sail, but it is at the upper limit for the board, and it just did not feel like the sail fit the board. Sluggish reactions and much harder to gybe. 104 sweet spot is between 6.0 and 5.5 for my weight. My best day ever on that board was on a MauiSails 5.8 Global. I don&#39;t think you should even consider it for an 8.2 sail.

The 115 does carry a larger sail, but my opinion is that you would not be at all happy with an 8.2 on that board. I have found no problems with either board in choppy conditions in 18-20 knots, so that should not be an issue for you.

As Ray has said, if you want to use the 8.2, you should look at a larger S-Type or even an iSonic which can carry a much larger sail for the same size(115).

Tks Ray and Dave for your respective answers...
I&#39;ll surely consider the ISonic board to carry larger sails.
For instance, the ISonic 105 is able to get a 8.5 sail size, so with my 8.2, would be suitable.